Pneumatically actuated strapping apparatus

ABSTRACT

A pneumatically actuated strapping apparatus for strapping plastic tape around a packaging item includes a motorized tensioning device, a motorized welding device for the plastic tape, and a pneumatic control device that has a first manually operated valve for operating the tensioning device and a second manually operated valve for operating the welding device. In order to spare an operator the trouble of obtaining essentially the same tensioning state of the plastic tape prior to the welding step each time a packaging job is repeated, a third valve is included which allows the welding device to be switched to an automatic operating mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation application under 37 CFR 1.53(b) of International Application Serial No. PCT/EP2012/005292, filed Dec. 20, 2012 entitled PNEUMATICALLY ACTUATED STRAPPING APPARATUS, which claims the benefit of German Application Serial No. 20 2011 109 483.2 filed Dec. 23, 2011, the entire contents of each of which are herein incorporated by reference.

BACKGROUND INFORMATION

The invention relates to a pneumatically actuated strapping apparatus for strapping a plastics tape around a package, comprising a motorized tensioning device and a motorized welding device for the plastics tape, and including a pneumatic control system, which has a first manually actuated valve for actuating the tensioning device and which has a second manually actuated valve for actuating the welding device.

Apparatuses of this type are known. The plastics tape is firstly placed in a loop around a package, wherein a first, free end forms a bottom band at a connecting point. The other end of the plastics tape loop is guided as a top band, together with the bottom band, at a welding point through the welding device, and subsequently runs to the tensioning device. A motorized friction wheel or a similar element, which grips the top band and thereby tautens the loop around the package, is then provided in the tensioning device.

Once the plastics tape is then wound tightly around the package, it is compressed in this state at the welding point where it runs through the welding device. There, a vibrating plate, as part of the welding device, is then lowered onto the bands lying one upon the other and is set in vibration. The vibration is generated by a motor via a gear mechanism. Due to this vibration, a relative movement ensues between the top and bottom band, which, owing to the friction which is hereupon generated, leads to local fusion of the thermoweldable plastics tape.

Following completion of the vibration movement and a short period of cooling, the top band and the bottom band are then welded together at the connecting point. The top band is then usually cut off next to the connecting point and the strapping apparatus can then be removed from the package around which the plastics tape is wound.

With the strapping apparatus which is described here, an operator can react very specifically to a wide variety of packages and adapt the tension of the plastics tape, for example, to the pressure sensitivity of a package. Once the plastics tape is placed as a loop around the package and inserted into the strapping apparatus, the operator actuates the tensioning device for the plastics tape via the first valve. As soon as the desired tension of the plastics tape and the package is reached, the second valve is actuated by the operator and the welding device can thereby be manually started up.

However, if equal packages are always to be strapped, this is felt in the long run to be very tiring for an operator. He must constantly try to reach a substantially equal tensioning state for the plastics strap, before then having to manually intervene in order to initiate the actuation of the welding device.

SUMMARY

An object of the present invention is to refine a strapping apparatus as described above, such that an operator, in the case of repetitive packing tasks, can be relieved of such monitoring duties.

This object is achieved according to the invention by virtue of the fact that a strapping apparatus has a third valve, with which the actuation of the welding device can be switched to automatic.

The invention has the advantage that a device which has many varied applications is provided.

On the one hand, it can be used in “manual mode” in cases in which it is important that an operator adapts the tension of the plastics tape, which is generated by the tensioning device, specifically to packages of very different types. It can also be used, however, when repetitive packaging tasks are to be executed. In the latter case, an operator, after a plastics tape has been guided around a package and the plastics tape has been inserted into the strapping apparatus, can make the latter work automatically, while he, if need be, attends also to other tasks.

Although there are already automatically working strapping apparatuses, these do not have the advantage of the here described device of being able to be used both for a manual and for an automated process. Instead, two apparatuses, which work either manually or automatically, had previously to be held available, thereby incurring increased costs for the procurement of two apparatuses.

In a preferred embodiment of the invention, the second, manually actuated valve for actuating the welding device and the third valve for switching the apparatus to automatic actuation of the welding device are provided as separate elements. On the one hand, less complex and thus more cost-effective components can thereby be used. On the other hand, however, the risk of unintentional operating error on the part of the operator is also reduced.

Having said that, it is also of course within the scope of the invention if the second valve and the third valve are configured such that they are mutually integrated in order that the second valve can be switched, so to speak, from a touch-based actuation setting into an automatic actuation setting.

Further advantages and features of the invention emerge from the following description of an illustrative embodiment, wherein:

The figure shows a pneumatic circuit diagram of a strapping apparatus.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE shows a pneumatic circuit diagram of a pneumatically actuated strapping apparatus.

DETAILED DESCRIPTION

Through actuation of the tension valve 1 via the tension valve lever a, compressed air can flow to the air motor 13, which is reversible in terms of its direction of rotation. There, the compressed air is expanded in a known manner, whereby the air motor is driven. The waste air is conducted outward via a sound damper 10. The idle air which is generated in the air motor 13 in the course of its rotation is evacuated outward via a rapid venting valve 12 and a sound damper 15.

By the air motor 13 is driven a friction wheel (not represented), with which a plastics strip guided through a strapping apparatus is tensioned after having been placed in a loop around a package. The maximum tensioning force which is here applied by this friction wheel to the plastics tape is determined via a tensioning force control valve 8.

As soon as the friction wheel has applied a desired, or else the maximum tension to the plastics tape, the welding start valve 2 is actuated by manual actuation of the welding valve key b.

As a result, on the one hand compressed air flows to the air motor 13 and drives this around the opposite direction. After its resulting expansion, this compressed air is diverted back via the sound damper 10, while the idle air of the air motor is evacuated outward via the rapid venting valve 14 and a sound damper 16.

At the same time, a welding cylinder 11 is also actuated and lowered by a shuttle valve 7, and thus the plastics tape which lies in a loop around the package is pressed together at its two ends at a welding point, while being subjected to vibrations which result in the welding of the plastics tape. The vibrations are generated by the air motor 13, which, for this purpose, is connected to a vibrating plate via a gear mechanism.

The welding time during which the vibration, and thus the actual welding operation, takes place is determined by a welding time valve 9, which in this regard cooperates with a welding motor valve 6. Following expiry of the preset welding time, the welding motor valve 6 is actuated by the welding time valve 9, whereby the compressed air inflow to the air motor 13 is terminated and the pneumatic motor 13 thereby stops and thus also no longer generates any vibration.

Following accompanying termination of the welding operation, the welding cylinder 11 continues to be held for a short period in the lowered position in order to allow cooling of the welding point. The period which is required for this purpose is set via the cooling time valve 4, which, by influencing the welding cylinder valve 5, jointly controls the spring-induced lifting of the welding cylinder 11.

As a peculiarity in the here illustrated pneumatic circuit diagram can now be seen, in particular, the reversing valve 3, which can be actuated via a reversing lever c.

With this reversing valve 3, the welding start valve 2 is disconnected or overridden, and thus a manual start-up of the welding cycle by actuation of the valve is replaced by an automatic actuation for the welding cycle.

Once the tension desired for the plastics tape is reached, an operator thus does not have to manually start the welding operation, whereby an, in many situations, desired automation or partial automation of the strapping operation is enabled. 

What is claimed is:
 1. A pneumatically actuated strapping apparatus for strapping a plastics tape around a package, comprising: a motorized tensioning device; a motorized welding device for the plastics tape; and a pneumatic control system, having a first manually actuated valve for actuating the motorized tensioning device, a second valve for manual actuation of the motorized welding device, and a third valve, with which the actuation of the welding device can be switched to automatic.
 2. The strapping apparatus as claimed in claim 1, wherein the second manually actuated valve and the third valve are provided as separate elements.
 3. The strapping apparatus as claimed in claim 1, wherein the second manually actuated valve and the third valve are configured such that they are mutually integrated. 